Loomio
Wed 1 Feb 2017 5:08PM

Glossary

MF Mark Frohnmayer Public Seen by 404

We use a lot of words here that have technical meaning within voting systems, yet we might not all be on the same page about what they mean. I'll keep this post updated as people suggest definitions or redefinitions for key words or phrases in these discussions:

Ranked (Choice) Voting Systems: Voting systems that use the voters explicit or implied ranking of candidates to determine the winner.

Ranking: is a relationship between a set of items such that, for any two items, the first is either 'ranked higher than', 'ranked lower than' or 'ranked equal to' the second.

Strategic (or Tactical) Voting: insincerely expressing your vote in order to achieve a better outcome from the election. This can include voting for the "lesser evil" instead of your true favorite in systems where voting for a weaker first choice can cause the election of your least favorite, as well as misrepresenting support for subsequent preferences in order to achieve an overall better result.

Tyranny of the Majority involves a scenario in which a majority of an electorate places its own interests above, and at the expense and to the detriment of, those in the minority, where by that detriment constitutes active oppression comparable to that of a tyrant or despot.

SW

Sara Wolf Sun 5 Feb 2017 9:39AM

@wolftune Aaron just gave a really good explanation of the tyranny-of-the-majority concern and how it relates to SRV. I thought it should end up here in the glossary.

"51% of voters favor candidate A. 49% hate candidate A. Say that 100% of voters love candidates B and C with weak preference between them. Say there's some others, D, E, F so that the range isn't where B or C are the worst for anyone.

Well, that means B and C will have 100% of voters giving them 9, 8, or 7. Clearly, that's higher score than 51% of voters giving a 9. So, B and C will go to the runoff. 100% of voters will be satisfied (feel supportive of the winner), but 51% majority could be disappointed in not getting their favorite.

Now, if it's not 51% but 65% or 70%, then that could change things because not only would the scores get closer, but the majority status might be more obvious so bullet-voting by the majority becomes a safer strategy and they decide to just assert their tyranny-of-the-majority by giving everyone but A a 0 (or some of them do that).

... the only result Score Runoff gives in this sort of scenario is either a true majority winner from all candidates or the majority-favorite (among those who differentiate a preference in the runoff) of the top overall scoring candidates. This isn't tragic ever.

The Condorcet winner is not guaranteed in Score Runoff. A tyranny-of-the-majority winner is always the Condorcet winner. Any system that allows consensus candidates to possibly win over tyranny-of-the-majority does not support the Condorcet criterion."